Adam Bien's Weblog

Injecting Properties Into Java EE Applications

To make basic datatypes injectable into POJOs, like:

    private String greeting;

    private int intValue; will have to expose them first. The name of field may act as the lookup key:


import javax.enterprise.inject.Produces;
import javax.enterprise.inject.spi.Annotated;
import javax.enterprise.inject.spi.InjectionPoint;
import javax.inject.Inject;

public class Configurator {


    Instance<Map<String, String>> initialValues;

    public void init() { = //...
        for (Map<String, String> initial : initialValues) {

    public String getString(InjectionPoint ip) {
        String className = ip.getMember().getDeclaringClass().getName();
        String key = className + "." + ip.getMember().getName();
        String fieldName = computeKeyName(ip.getAnnotated(), key);

    String computeKeyName(Annotated annotated, String key) {
        Configurable annotation = annotated.getAnnotation(Configurable.class);
        return annotation == null ? key : annotation.value();


    public long getLong(InjectionPoint ip) {
        String stringValue = getString(ip);
        if (stringValue == null) {
            return 0;
        return Long.parseLong(stringValue);

The conventional field name as lookup key can be overridden with an annotation:

	String message;

The annotation is expects a single string which is going to be used as a key:

@Target({ElementType.FIELD, ElementType.METHOD})
public @interface Configurable {
    String value();

Now you only need to expose a datasource of your choice as Map<String, String>, like e.g. environment variables or System-properties to make them injectable:

import javax.enterprise.inject.Produces;

public class Initializer {

    public Map<String, String> getInitialConfiguration() {
    	//...fetch properties from wherever you like

"How to inject properties into Java EE apps" was one of the questions in the recent

The code above was taken from JCache Configurator for Java EE -- a one-class Java EE framework. See also the Java Magazine article Convention Over Configuration in Java EE 6.

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But what if you need to configure a JPA Entity, where Injection is not available?

Posted by Alex on February 09, 2016 at 08:39 AM CET #

Wow, this is the most contrived way to use properties I have ever seen!

Posted by javaservant on February 09, 2016 at 01:39 PM CET #

I think that's a generic solution. Is there any faster, shorter, easier way to inject values in .properties files into POJOs? I need some convention over configuration like @Inject(from="application.properites", key="some.key") private String someKey; without any helper, producer ... classes. Then I need to change the .properties file for different environment. So maybe @Profile("local") @Inject(from="", key="some.key") will get the value from Finally, this looks like Spring :-)

Posted by Thai on February 10, 2016 at 07:36 PM CET #

Thank you Adam. This is a fantastic, clean and concise solution. Our team are now using a database driven version of this example.

Our solution needed the annotation to have: @Nonbinding public String value();

Posted by Geoff Hayward on February 16, 2016 at 02:17 PM CET #

Seems like a good old singleton.
How about it like this:
public class MySettings {
Map<String, Object> settings;
Object getSetting(String name) {...}


Much simpler. Still configurable, injectable, testable... Or not?

Posted by Matyas on February 18, 2016 at 03:42 PM CET #

If you need a tool to translate .properties files, check out the localization management platform

It's easy to set up and free to use up to 1000 strings.

Posted by Parov on June 08, 2016 at 03:30 PM CEST #

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